Adaptive Current Regulation for Solid State Lighting

Abstract

Exemplary embodiments provide an apparatus, system and method for power conversion to provide power to solid state lighting, and which may be coupled to a first switch, such as a dimmer switch. An exemplary system comprises: a switching power supply; solid state lighting; a first adaptive interface circuit to provide a resistive impedance to the first switch and conduct current from the first switch in a default mode; and a second adaptive interface circuit to create a resonant process. An exemplary apparatus comprises: a switching power supply; and an adaptive interface circuit comprising a resistive impedance coupled in series to a reactive impedance to conduct current from the first switch in a first current path in a default mode, and further comprising a second switch coupled to the reactive impedance to conduct current from the first switch in a second current path, with the adaptive interface circuit further damping oscillation when the first switch turns on.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is related to and is a continuation-in-part of U.S. patent application Ser. No. 12 / 639,255, filed Dec. 16, 2009, inventors Anatoly Shteynberg et al., entitled “Adaptive Current Regulation for Solid State Lighting”, which is related to and is a continuation-in-part of U.S. patent application Ser. No. 11 / 655,558, filed Jan. 19, 2007, inventors Anatoly Shteynberg et al., entitled “Impedance Matching Circuit for Current Regulation of Solid State Lighting”, now U.S. Pat. No. 7,656,103 issued Feb. 2, 2010, which claims priority to and is a conversion of U.S. Provisional Patent Application Ser. No. 60 / 760,157, filed Jan. 20, 2006, inventors Anatoly Shteynberg et al., entitled “Off-Line LED Driver with Phase Modulation”, all of which are commonly assigned herewith, the contents of each of which are incorporated herein by reference with the same full force and effect as if set forth in their entireties herein, and with priority cl...

AI Technical Summary

Benefits of technology

[0012]The exemplary embodiments of the present invention provide numerous advantages. The exemplary embodiments allow for solid state lighting, such as LEDs, to be utilized with the currently existing lighting infrastructure, including Edison sockets, and to be controlled by any of a variety of switches, such as phase modulating dimmer switches, which would otherwise cause significant operation problems for conventional switching power supplies or current regulators. The exemplary embodiments further allow for sophisticated control of the output brightness or intensity of such solid state lighting, and may be implemented using fewer and comparatively lower cost components. In addition, the exemplary embodiments may be utilized for stand-alone solid state lighting systems, or may be utilized in parallel with other types of existing lighting systems, such as incandescent lamps.

[0013]Exemplary embodiments of the present invention not only recognize and accommodate various states of switches, such as phase modulating dimmer switches, but further utilize a novel insight to also concurrently recognize and accommodate various states of a switching power supply, such that both a phase modulating dimmer switch and a switching power supply operate together, seamlessly and with substantial stability. More particularly, the exemplary embodiments recognize and accommodate at least three states of a phase modulating dimmer switch, namely, a first state in which the dimmer switch is not conducting but during which a triggering capacitor (C1, 77) is charging; a second state in which the dimmer switch has turned on and requires a latching current; and a third state in which the dimmer switch is fully conducting and requires a holding current. Concurrently, in combination with the states of the switch, the exemplary embodiments recognize and accommodate at least three states, and in various embodiments four states, of a switching power supply, namely, a first, start up state of the switching power supply, during which it generates its power supply (VCC voltage level); a second, gradual (graduated or “soft”) start state of the switching power supply, during which it ramps up its provision of power to a load (such as LEDs) (e.g., through pulse width modulation (“PWM”) switching) from start up to a full operational mode; a third state, during which the switching power supply is in a full operational mode; and an optional fourth state, during which the switching power supply may experience an abnormal or atypical operation and enter a protective operating mode. For each combination of states of the switch (e.g., dimmer switch) and switching power supply, using corresponding criteria for stable operation, the exemplary embodiments provide a substantially matching electrical environment to meet such criteria for stable operation of both the switch and the switching power supply, enabling seamless and stable operation of both components. In various exemplary embodiments, the same type of substantially matching electrical environment may be utilized for multiple combinations of states, and in other instances, other types of substantially matching electrical environments will be utilized for a selected combination of states of the switch and switching power supply.

[0048]In another exemplary embodiment, system for power conversion is disclosed, the system couplable to a first switch coupled to an alternating current (AC) power source, with the system comprising: a switching power supply; solid state lighting coupled to the switching power supply; a first adaptive interface circuit comprising a resistive impedance coupled in series to a reactive impedance to conduct current from the first switch in a first current path in a default mode; and a second adaptive interface circuit comprising a second switch coupled to the reactive impedance to conduct current from the first switch in a second current path, the first and second adaptive interface circuits further damping oscillation when the first switch turns on.

Problems solved by technology

Many of these power supplies (i.e., drivers) are effectively incompatible with the existing lighting system infrastructure, such as the lighting systems typically utilized for incandescent or fluorescent lighting, such as infrastructure generally utilizing phase-modulating “dimmer” switches to alter the brightness or intensity of light output from incandescent bulbs.

Accordingly, replacement of incandescent lamps by LEDs is facing a challenge: either do a complete rewiring of the lighting infrastructure, which is expensive and unlikely to occur, or develop new LED drivers compatible with commercially available and already installed dimmers switches.

This proposal is complicated, requires excessively many components to implement, and is not particularly oriented to AC (alternating current) utility lighting.

When coupled with a dimmer, however, its LED regulation is poor and it does not completely support stable operation of the dimmer in the full range of output loads, specifically when both incandescent and LED lamps are being used in parallel.

Typical prior art, off-line AC / DC converters that drive LEDs using phase modulation from a dimmer switch have several problems associated with providing a quality drive to LEDs, such as: (1) phase modulation from a dimmer switch can produce a low frequency (about 120 Hz) in the optical output, referred to as “flicker”, which can be detected by a human eye or otherwise create a reaction in people to the oscillating light; (2) filtering the input voltage may require quite a substantial value of the input capacitor, compromising both the size of the converter and its useful life; (3) when the triac 80 is turned on, a large inrush current may be created, due to a low impedance of the input filter, which may damage elements of both the dimmer switch 75 and any LED driver; and (4) power management controllers are typically not designed to operate in an environment having phase modulation of input voltage and could malfunction.

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